Circuit breaker



March 7, 1939. VON HQORN 2,150,012

C IRCUIT BREAKER Filed Jan. 27, 1937 Inventor;

)0 3 244 620 .y H's Attorney Fred G. von Ho Th,

Patented Mar. 7, 1939 UNITED STATES PATENT OFFICE CIRCUIT BREAKER Fred G. von Hoorn, Bridgeport, Conn., asslgnor to General Electric Company, a. corporation of New York My invention relates to circuit breakers, more particularly to thermal circuit breakers, and has for its object a simple, reliable and inexpensive device of this character.

My invention has special application in circuit breakers of small physical size, such as used in branch electric lighting circuits, which are operable manually to open and close the circuit, but

which also are responsive to excessive current to conditions to open the circuit independently of the operating handle. Circuit breakers embodying my invention may be constructed with relatively small overall dimensions such that they can be mounted in the wall of a building in a 25 agement with an intermediate portion of the switch member to move the switch member about its secured end as a pivot between the closed and openposition to thereby operate switch contacts to close and open an electric circuit.

so For a more complete understanding of my invention reference should be had to the accompanying drawing, Fig. 1 of which is a view in section of a circuit breaker embodying my invention showing the device in closed circuit posi- 35 tion, Fig. 2 is a view similar to Fig. 1, but showing the device in theTnanually operated open position, Fig. 31s a view similar to Figs. 1 and 2, but showing the device in the overload responsive automatic open position, while Fig.4 is a 40 transverse sectional view taken along the line 4, 4 of Fig. 2 and looking in the direction of the arrows.

Referring to the drawing, I have shown my. invention as embodied in a circuit breaker of small 45 physical size; such as might be mounted in the wall of a building, in place of the conventional snap switch, in order to control the lights of a particular branch circuit. It obviously, however, 50 has other uses such, for example, as the entrance switch to the building, and in the control of the circuits of various industrial electrical apparatus, In each case, of course, the size and characteristics of the device will be'selected to take 55 care of the desired normal current and overload current. It is especially adapted for use on alternating current circuits and in such circuits it performs the safety function of a fuse interrupting currents of 5000 to 10,000 amps. or more depending upon the size of the breaker. 5

The breaker comprises, in the form shown, a suitable rectangular base or casing i0 made of electrically insulating material such as a molded phenolic condensation product. This base in is formed with a relatively thick bottom wall, centrally of which is provided a longitudinally extending slot H in which is mounted a switch arm or member l2 made of a suitably electrically conducting material such as copper. This member I2 is a strip or blade substantially rectangular in shape as shown. The slot H is just wide enough, i. e., its dimension in a direction perpendicular to the drawing Figs. 1 to 3, inclusive, is just great enough to permit free movement of the switch member in the slot, the walls of the slot forming a guide for the switch member.

This, switch member I2 is operated manually to close or open the circuit by means of an operating member or handle l3, also made of a suitably molded electrically insulating material. The handle I3 is pivotally mounted on a pin I l secured to the side walls of the casing l0. It is provided with an operating portion extension [3a having an operating surface on its lower end consisting of three fiat, rectangular portions i5, 80 I6 and l! which are located at different distances from the pivot 44, these distances increasing in the order mentioned. The cam faces are furthermore arranged in a predetermined angular and positional relationship with the pivot M to provide the operating characteristics hereinafter pointed out. Upon suitable movement of the handle, they selectively engage the upper edge 01' the switch member and thereby operate the switch member to control suitable circuit making and breaking contacts. The switch member l2 and the handle are resiliently connected together and biased toward each other by means 01' two helical tension springs i8 and I9, one on each side. At their lower ends the springs I8 and I9 are attached to the switch member l2 by means of a pin 20 which extends transversely through the switch member at a point near the center of the switch member. The upper ends of the springs l8 and it are attached to the handle through the agency of a pin 2! which extends transversely through the handle in parallel relation with the pivot pin l4 and just below the pivot-pin, i. e., on the side the pin 2I, which is the point of attachment of the springs to the handle, provides for a small component of the force exerted by the springs I8 and I9 tending to rotate the handle I3 in a clockwise direction when the handle is in the closed circuit position so that the cam face I6 is held in engagement with the switch member, as shown in Fig. 1. This assures that the handle is held in its proper closed circuit position and thereby indicates that condition of the switch. Without this clockwise bias the handle might rotate slightly in a counterclockwise direction, it being otherwise free to do so, to the position indicated in Fig. 3 which is the automatic position. This is because the cam face It is positioned on the handle so as to lie on the right-hand side of a plane containing the lines of action, 1. e. axes, of the springs I8 and 59.

A further function of the pin is to secure the switch member against longitudinal movement in the slot II. To efiect this, grooves 22 and 23 are provided in opposite walls of the slot, these grooves being directly opposite each other and extending vertically, as viewed in Figs. 1 to 3 inclusive, in transverse relation with the slot II. These grooves 22 and 23 are in position to receive the ends of the pin 20 and are just wide enough to permit free sliding movement of the ends of the pins. The walls of the grooves thus define the vertical movement of the pin 20 and prevent movement of the switch member I2 longitudinally. The slots 22 and 23 furthermore are substantially below the pin l4, as shown, so that the path of movement of the pin 20 substantially intersects the pin I4. Wider transverse grooves 22a. and 23a. are provided in the base to provide for freedom of movement of the springs I8 and I9.

When the switch is in its closed position, as shown in Fig. 1, the left-hand end of the switch member I2 rests against and is secured by the lower end of a thermal current responsive member, shown as a bi-metallic strip 24, while the other end of the switch member l2 bear's against a stationary switch contact 25. Thus in this position the force of the spring is applied to move the switch member upward against the thermostat and the stationary contact, except for the relatively small component of spring force tending to rotate the handle in a clockwise direction and thus hold the cam face I6 against the switch member. The upper end of the strip 24 is secured to an electrically conducting lead 26 forming a support for the thermostat and secured at its other end to the base II] by means of a screw 21 which also serves as a binding post for connection with an electric circuit. The lower end of the thermostat bar 24 is electrically connected with the switch member I2 by means of a flexible conductor 28, the ends of the conductor being suitably secured, as by welding, to the thermostat bar and the switch member. This flexible conductor 28 is preferably made of strands of copper which are suitably twisted or braided together. It will be understood that the wall of the slot II on the side next to the conductor 28 is cut away somewhat in the vicinity of the conductor 28 to provide space for it.

Also the left end of the switch member is cut down to provide a shoulder 29 against which the end of the thermostat comes to rests This prevents the end of the thermostat from moving an excessive distance to the right over the upper edge of the switch member, in response to low of the pin opposite the handle. This position of temperatures, and obviates the excessive friction in that event to be overcome by the thermostat in moving to the left to release the switch member in response to an excessive current.

The stationary switch contact 25 is secured to the casing II! by means of a screw 30 which serves as a binding post for connection with an electric circuit. As shown, the right-hand end of the switch member I2 is suitably shaped to form a switch contact 3|. Obviously, contacting surfaces made of materials resistant to arcing will be used, if desired, on these contacts.

A suitable cover 32, shown as made of electrically insulating material, is provided for the casing, the upper wall of the cover being provided with an opening 33 through which the handle I3 extends and the wall being depressed around the handle to a point adjacentthe pivot of the handle so as to fit as closely as possible around the handle. 2

The electric circuit through the switch when in the closed position, as shown in Fig. 1, may be traced from the binding post or terminal 21, the conductor 26, the bimetallic thermostat 24, the flexible conductor 28, switch member I2 and contacts 3| and 25 to the opposite binding post or terminal 30.

From the closed circuit position shown in Fig. 1 the handle I3 may be moved in a clockwise direction to the position in Fig. 2 to thereby bring the cam face I'I into engagement with the switch member. Since the face I! is located at a greater distance from the pivot l4 than the face IS, the

switch member I2 is thereby swung downward, its left-hand end pivoting on the end of the thermostat 24, whereby the right-hand end is moved away from the stationary contact 25 and the electric circuit thereby broken. In this open position, the switch member I2 is held firmly against the cam face II by the springs 18 and I9, the position of the cam face on the handle being such that the plane of the lines of force of the springs passes substantially through the middle of the cam face and at right angles thereto. This effectively holds the handle and the switch member together in the positions shown, thereby preventing upward movement of the right-hand end of the contact member toward the closed position. I

It will be observed that upon initial clockwise movement from the closed position of Fig. 1, the handle engages the switch member at a point substantially to the right of the pin 20 and the plane of the lines of force of the springs. sequently the springs hold the left-hand end at that time securely against the end of the thermostat 24.

With the switch closed, in the event of a predetermined maximum current the thermostat 24 is heated by this current to such an extent that the lower end is moved toward the left by distortion of the thermostat, as indicated in Fig. 3, sufficiently to release the left-hand end of the switch member, which end is immediately snapped upward by the springs to the automatic open position shown in Fig. 3. This movement is initially and chiefly a pivotal one around the corner 34 on the lower end of the handle at the intersection of the cam faces I5 and I6, the pin 20 moving upward. More particularly the switch member I2 when released pivots about the pivot 34 until its right-hand end strikes the bottom of the casing at the point 35. Thereafter it pivots about the point 35 to the final position of Fig. 3. Concurrent with this final Conpivotal movement, the handle is moved slightly, but visibly, in'a-counterclockwise direction from the position of Fig. 1 to the position of Fig. 3, until the cam face I5 is swung into engagement with the switch member. The handle thus gives an indication of this automatic open condition of the breaker.

In the automatic open position, as in the manual open position of Fig. 2, the plane of the line of action of the springs l8 and I 9 passes through the cam face I5 at substantially the middle of the cam face and at right angles to the cam face whereby the handle and switch member are resiliently secured together in definite relative angular positions, and in the definite angular positions with respect to the base l0 as previously pointed out. In other words the springs pull the switch member and the handle together bringing the switch member I! against the cam face l5 and in so doing position angularly both the handle and the switch member.

For the purpose of making this automatic open or tripped position of the handle more readily discernible, an indicating mark 36 is provided across the edge of the handle, this mark being in position to be obscured from View by the edge of the cover 32 when the handle is in the closed narrow slot ll.

position of Fig. 1. For example, the handle may be black and the mark may be white. The counterclockwise movement of the handle from Fig. 1 and Fig. 2 brings this mark into view.

It will be observed that the switch contacts 25 and 3! are separated from the handle and spring operating mechanism by the wall 31 of the casing. ,These contacts are, as shown, located in a rectangular chamber 38 in the casing l0 adjoining the main chamber 39 in which the handle l3 and other operating mechanism are located. These two chambers are completely isolated by the electrically insulating walls of the casing except for the opening provided by the relatively While the chamber 38 is shown open on two sides, it will be understood that the circuit breaker will preferably be mounted in a second casing or box with suitable means for completing .the closure and the venting of the chamber 38 if desired. For example the circuit breakers may be mounted single and in groups in metal boxes.

What I claim as new and desire to secure by Letters Patent of the United States is: I

1. A circuit breaker comprising a switch member, a current responsive holding device, a stationary contact spaced therefrom, spring means biasing said switch member to closed circuit position with its ends in engagement respectively with said holding device and said stationary contact, a pivoted handle having an operatingportion movable into engagement with an intermediate portion of said switch member to move said switch member about said holding device to an open circuit position, said holding device releasing said switch member in response to a predetermined current through said switch member whereupon said spring means moves said switch member about said handle as a pivot to disengage said stationary contact.

2. A circuit breaker comprising a switch member having a substantially straight operating surface intermediate its ends, a pivoted handle having an operating portion provided with a plurality of surfaces arranged at difierent dis tances from the pivot of said handle, spring means for pressing said switch member against said handle with said intermediate portion of said switch member engaging a selected one of said surfaces, means for securing one end of said switch member whereby movement of said handle to bring another one of said surfaces into engagement with said switch member moves the other end of said switch member, and circuit controlling means operated by the movable end of said switch member.

3. A circuit breaker comprising a switch blade, a pivoted handle, spring means for biasing said blade toward the pivot of said handle to bring an intermediate portion of said blade against said handle, said handle having an operating portion provided with a plurality of faces arranged at difierent distances from the pivot of said handle for moving said blade, current responsive means for securing one end of said blade, and switch contacts operated by the other end of said blade.

4. A circuit breaker comprising a switch blade, a thermal current holding device, a stationary contact spaced therefrom, an operating handle pivotally mounted between said holding device and said stationary contact, spring means connecting said handle and an intermediate portion of said blade together to thereby bias said blade to a closed circuit position with its ends in engagement respectively with said holding device and said stationary contact, and an operating portion on said handle provided with an operating face for holding said blade in its open position and with another operating face for positioning said handle when said blade is released by said thermal device.

5. A circuit breaker comprising a switch member, current responsive holding means normally securing one end of said switch member, means for biasing said switch member to a closed circuit position, a handle engaging said switch member to operate said switch member about said holding means between closed and open position, said switch member moving about said handle to an automatic open position when released by said holding means, and means cooperating between said handle and said switch member for positioning said handle when said switch member moves to said automatic open position.

6. A circuit breaker comprising a switch blade, a current responsive holding device, a stationary contact spaced therefrom, a spring biasing said blade to closed circuit position with its ends in engagement respectively with said-holding device and said stationary contact, a pivoted handle having an operating portion provided with a positioning face and an operating face movable into engagement with an intermediate portion of said blade to move said blade about said holding device to an open circuit position, said holding device releasing said blade in response to a predetermined current through said blade whereupon said spring means moves said blade about said handle as a pivot to disengage said stationary contact and bring said blade and said positioning face into engagement with each other whereby said handle is positioned to show the position of said blade.

7. A circuit breaker comprising a support provided with a slot and with oppositely disposed parallel grooves in the walls of said slot, a switch member movable in said slot, a transversely extending guide pin secured to said blade intermediate the ends of said blade and having its.

ends slidable in said grooves, a handle of electrlcally insulating material, means for pivotally mounting said handle on a pivot substantially in alinement with said grooves, a tension spring connecting said switch member to said handle, said handle being provided with a plurality of faces located at different distances from said pivot arranged for engagement with said switch member selectively in dependence upon the position of said handle; thermal load responsive means securing one end of said switch member whereby movement of said handle moves said.

switch member about said secured end, and

switch contacts operated by said switch member.

8. A circuit breakercomprising a support provided with a slot and with.transversely'extending parallel grooves in opposite walls of said slot, an electrically conductingswitch blade insaid slot, a transversely extending guide pin secured to said blade intermediate the ends of said blade and having its ends slidable in said grooves, a

handle of electrically insulating material, means for pivotally mounting said handle on a pivot substantially in alinement with said grooves, an operating extension secured to said handle on the opposite side of said pivot from said handle, said extension being provided with at least three fiat operating faces arranged at diiferent distances from said pivot and in a predetermined angular and positional relation with said pivot such that movement of said handle moves two of said faces selectively in engagement with said blade to operate said blade to its closed and open circuit positions, spring means having its ends connected respectively to said handle and said blade for biasing said blade toward said handle, the connection between said spring means and said blade being efiected through said pin and said spring means being connected to said handle at a point on the side of said pivot opposite said handle, thermal current responsive means normally securing one end of said blade but releasing said means pressessaid blade against said thermal current reponsive means and said stationary contact whereby when said thermal current responsive means releases said blade upon the occurrence of a predetermined current said spring means moves said blade about the intersection of said closed circuit face and said third face as a pivot to thereby disengage the opposite end of said blade from said stationary contact and move said blade and said third face into engagement with each other to thereby effect movement of said handle to indicate the position of said blade.

9. A circuit controlling device comprising an operating member, a pivoted handle having an operating portion provided with a surface having portions arranged'at different distances from the pivot of said handle, spring means for biasing said said operating member, said spring means moving said operating member about said surface as a pivot when said operating member is released by said current responsive means.

10. A circuit controlling device comprising an operating member, a pivoted handle having an operating portion provided with a plurality of surfaces arranged at different distances from the pivot of said handle, said operatingportion being made of electrically insulating material,

termediate portion of said operating member against one of said surfaces, thermally responsive means for securing one point of said operating member whereby movement of said handle moves said operating member, andcireuit controlling means actuated by said operating member, said spring means moving said operating member about said handle as a pivot when said operating member is released by said thermally responsive device.

11. A circuit breaker comprising an operating member, a pivoted handle having an operating portion provided with a plurality of surfaces arranged at different distances from the pivot of said handle, said operating portion being made of electrically insulating material, spring means for biasing said operating member toward the pivot of said handle to bring an intermediate portion of said operating member against one of said surfaces, current responsive means for securing one end of said operating member whereby movement of said handle moves the other end of said operating member, and circuit controlling means actuated by the movable and of said operating member including means for connecting said operating member in an electric circuit, said spring means moving said operating member about said portion of said handle as a pivot when said operating member is released by said current responsive device.

12. A circuit breaker comprising a switch member, a pivoted handle having an operating portion provided with a plurality of surfaces ar ranged at different distances from the pivot of said handle, said operating portion being made of electrically insulating material, spring means for pressing an intermediate portion of said switch member against one of said surfaces, current responsive means for securing one end of said switch member whereby movement of said handle to bring another of said surfaces into engagement with said switch member moves the other end of said switch member, and circuit controlling means operated by the movable end of said switch member including means for connecting said switch member in an electric circuit, said spring means moving said switch member about said operating portion of said handle as a, pivot when said switch member is released by said current responsive means.

13. A circuit breaker comprising a support made of electrically insulating material, an elongated switch member of electrically conducting material mounted on said support, a bimetallicthermostat, a stationary contact spaced from said thermostat, an operating member mounted for predetermined movement between said thermostat and said contact, a spring engaging said switch member so as to bias said member with the ends of said member in engagement with said thermostat and said stationary contact respectively, an operating portion on said operating member made ofv insulating material provided with a cam face movable to engage said switch member and move said switch member about said thermostat as a pivot to disengage said stationary contact, and means connecting said thermostat and said switch memberin a circuit with said stationary contact whereby said switch member is released by said thermostat in response to a predetermined current in said circuit, said switch member being thereupon moved by said spring about said handle as a pivot to an open circuit position.

14. A circuit breaker comprising a support made of electrically insulating material, an elon gated switch member of electrically conducting material mounted on said support, guide means substantially preventing longitudinal movement of said switch member on said support, a bimetallic thermostat, a stationary contact spaced from said thermostat, an operating member mounted for predetermined movement between said thermostat and said contact, a spring engaging said switch member so as to bias said switch member laterally with the ends of said switch member in engagement with said thermostat and said stationary contact respectively, an operating portion on said operating member made of insulating material provided with a cam face movable to engage said switch member and move said switch member about said thermostat as a pivot to disengage said stationary contact, and means connecting said thermostat and said switch member in a. circuit with said stationary contact whereby said switch member is released by said thermostat in response to a predetermined current in said circuit, said switch member being thereupon moved by said spring about said handle as a pivot to an open circuit position.

15. A circuit breaker comprising a support made of electrically insulating material, an elongated switch member of electrically conducting material mounted on said support, a guide pin on said switch member cooperating with said support to prevent longitudinal movement oi said switch member on said support, a bimetallic thermostat, a stationary contact spaced from said thermostat, an operating handle mounted for pivotal movement between said thermostat and said contact, a spring having one end connected to said pin and its other end connected to said handle at a point near said pivot so as to bias said switch member laterally with the ends of said switch member in engagement with said thermostat and said stationary contact respectively, an operating portion on said handle made of insulating material provided with a cam face movable to engage said switch member and move said switch member about said thermostat as a pivot to disengage said stationary contact, said handle being biased by said spring to bring said operating portion into engagement with said switch member, and means connecting said thermostat and said switch member in a circuit with said stationary contact whereby said switch member is released by said thermostat in response to a predetermined current in said circuit, said switch member being thereupon moved by said spring about said handle as a pivot to an open circuit position.

16. A circuit breaker comprising a switch member, means mounting said switch member for movement between open and closed circuit positions, current responsive means normally securing a point of said switch member, means biasing said switch member to one of said positions about said point as a pivot and a handle having an operating portion engaging said switch member to move asid switch member about said point between open and closed circuit position, said biasing means moving said switch member about said portion as a pivot to its open circuit position when said switch member is released by said current responsive device and said handle being moved thereby to another position.

17 A circuit breaker comprising a switch member, means mounting said switch member for pivotal movement about a plurality of points between open and closed circuit positions, a current responsive device normally securing a point or said switch member, a spring biasing said switch member to one of said positions about said point as a pivot and an operating member having a portion movable into engagement with said switch member to thereby move said switch member to the other of said positions against the force of said spring, said operating member being held in said other position by said switch member, said spring moving said switch member about said portion as a pivot to its open circuit position when said switch member is released by said current responsive device and said operating member being thereby moved to a predetermined position by the force applied thereto by said switch member.

18. A circuit breaker comprising a switch member, means mounting said switch member for pivotal movement about a plurality of points between open and closed circuit positions, a current responsive device normally securing one end of said switch member, a spring biasing said switch member to one of said positions about said end as a pivot and a pivoted operating member having a portion movable into engagement with said switch member to a position between said switch member and the pivot of said operating member to thereby move said switch member to the other of said positions against the force of said spring, said portion being thereby held between said switch member and the pivot of said operating member, said spring moving said switch member about said portion as a pivot when said switch member is released by said current responsive device and said operating member being thereby biased to a predetermined position by the force applied thereto by said switch member.

19. A circuit breaker comprising a switch arm, means mounting said switch arm for pivotal movement about a plurality of points between open and closed circuit positions, a current responsive device normally securing one end of said switch arm, a spring biasing said switch arm to one of said positions about said end as a pivot, a pivoted operating handle having a portion movable into engagement with said switch arm to thereby move said switch arm to the other of said positions against the force of said spring, said operating handle being held in said other position by said switch arm, said spring moving said switch arm about said handle portion as a pivot to its open circuit position when said switch arm is released by said current responsive device, and guide means controlling the longitudinal position of said switch arm so that said switch arm moves about said handle portion into engagement with a different portion thereof to apply a force to move said handle to a different position.

FRED G. VON HOORN. 

